RJ03-Reflective Journal Entry 3- Assessment - Due Saturday, March 13, 2011
Identify a GSE and create a learning performance that combines evidence of understanding a critical concept with writing a good scientific explanation for a topic in your next unit. Provide a link in your description to the appropriate GSE.
Create a specific rubric for this scientific explanation.
Describe a difficulty or misconception that this activity might surface.
Describe you might use this assignment to provideformativefeedback to your students.
GSE: **PS2 (Ext) - 6**Students demonstrate an understanding of physical, chemical, and nuclear changes by… 6aa using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions. Learning Performance:
Antacid tablets react with the hydrochloric acid in the stomach to ease indigestion. Baking soda (NaHCO3) is often used as an antacid because it takes part in the following reaction: NaHCO3 + HCl ---> NaCl + H2O + CO2. Milk of magnesia (Mg(OH)2) is also used as an antacid because it takes part in the following reaction: Mg(OH)2 + HCl --> 2 H2O + MgCl2. Determine which antacid is more effective per gram. Write a scientific explanation to support your answer.
Rubric:
Level 0
Level 1
Level 2
Claim
Does not make a claim, or makes an inaccurate claim.
States both antacids are equally effective or specifies the wrong antacid.
Makes an accurate but incomplete claim
Vague statement, like "one antacid is more effective."
Makes an accurate and complete claim.
Explicitely states "Milk of magnesia (Mg(OH)2) is more effective than baking soda (NaHCO3) per gram."
Evidence
Does not provide evidence, or only provides inappropriate evidence (evidence that does not support claim).
Provides inappropriate data, such as "baking soda and milk of magnesia have different masses", or provides vague evidence such as "the equation is my evidence"
Provides appropriate, but insufficient evidence to support claim. May include some inappropriate evidence.
Provides a written explanation but does not show molar ratio calculation.
Provides appropriate and sufficient evidence to support claim.
Provides a written explanation as well as molar ratio calculations.
Reasoning
Does not provide reasoning, or only provides reasoning that does not link evidence to claim.
Provideds an inappropriate reasoning statement like "more grams of reactants make more grams of products" or does not provide any reasoning.
Provides reasoning that links the claim and evidence. Repeats the evidence and/or includes some sufficient principles, but not sufficient.
States that balanced equations provide molar ratios, but does not link reasoning to evidence.
Provides reasoning that links evidence to claim. Includes appropriate and sufficient scientific principles.
Explains that balanced equations provide molar ratios and that molar ratios help us predict how much of one reactant is needed to react with another to produce a product. links this reasoning directly to evidence.
Difficulties/Misconceptions:
Some difficulties that students may have with this assignment is applying their knowledge of molar ratios to draw a conclusion about which antacid is more effective. A common misconsception is that a 1:1 molar ratio means that they are equal and are therefore more effective. They may think that they would need less baking soda to neutralize the acid than milk of mangnesia. In actuality, the 1:2 molar ratio shos that milk of magnesia neutralizes twice as much acid than baking soda does.
Formative Feedback:
I will grade the scientific explanations using the rubric I developed above. In addition to giving students the graded rubric, I will also provide written feedback on their explanations. Such feedback will include what they did well, what could be improved and suggestions for making the explanation more complete. This assignment will be very useful in many ways. It will provide me feedback in how well students understand the concepts of molar ratios and stoichiometry, it will highlight any misconceptions or difficulties students have, and it will provide students with feedback about what they do well and how they can improve.
GSE:
**PS2 (Ext) - 6** Students demonstrate an understanding of physical, chemical, and nuclear changes by…
6aa using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions.
Learning Performance:
Antacid tablets react with the hydrochloric acid in the stomach to ease indigestion. Baking soda (NaHCO3) is often used as an antacid because it takes part in the following reaction: NaHCO3 + HCl ---> NaCl + H2O + CO2. Milk of magnesia (Mg(OH)2) is also used as an antacid because it takes part in the following reaction: Mg(OH)2 + HCl --> 2 H2O + MgCl2. Determine which antacid is more effective per gram. Write a scientific explanation to support your answer.
Rubric:
States both antacids are equally effective or specifies the wrong antacid.
Vague statement, like "one antacid is more effective."
Explicitely states "Milk of magnesia (Mg(OH)2) is more effective than baking soda (NaHCO3) per gram."
Provides inappropriate data, such as "baking soda and milk of magnesia have different masses", or provides vague evidence such as "the equation is my evidence"
Provides a written explanation but does not show molar ratio calculation.
Provides a written explanation as well as molar ratio calculations.
Provideds an inappropriate reasoning statement like "more grams of reactants make more grams of products" or does not provide any reasoning.
States that balanced equations provide molar ratios, but does not link reasoning to evidence.
Explains that balanced equations provide molar ratios and that molar ratios help us predict how much of one reactant is needed to react with another to produce a product. links this reasoning directly to evidence.
Difficulties/Misconceptions:
Some difficulties that students may have with this assignment is applying their knowledge of molar ratios to draw a conclusion about which antacid is more effective. A common misconsception is that a 1:1 molar ratio means that they are equal and are therefore more effective. They may think that they would need less baking soda to neutralize the acid than milk of mangnesia. In actuality, the 1:2 molar ratio shos that milk of magnesia neutralizes twice as much acid than baking soda does.
Formative Feedback:
I will grade the scientific explanations using the rubric I developed above. In addition to giving students the graded rubric, I will also provide written feedback on their explanations. Such feedback will include what they did well, what could be improved and suggestions for making the explanation more complete. This assignment will be very useful in many ways. It will provide me feedback in how well students understand the concepts of molar ratios and stoichiometry, it will highlight any misconceptions or difficulties students have, and it will provide students with feedback about what they do well and how they can improve.